Yeah run them when it is really cold out, I guess around zero. But I have also heard that you should/could run the heated carbs on when there is alot of snow dust and powder. I usually forget to turn them on haha I just make sure to run some dry gas through the sled often.
Yeah it says 40 but ignore that. how many times do you ride a snowmobile at 40 degrees? not too many. My dealer recommeds no warmer than 20 degrees or extreme cold. Basically anything below zero. If you do use them your asking for problems. Bad fuel mileage, fouled plugs, and you just dont need them.
Used them once last january in the UP when it was -15 for a high. didn't tell any difference. besides cold gas burns better anyway. leave them off unless you have problems. and then just sit and laugh at the yamaha guys when they have to go back into the bar and ask the bartender for a glass of hot water to dump on their carbs to get started again. hahahahahahahaha. what were the japs thinking on that one?
The flatsides were having some iceing problems when riding in snow dust and freezing rain. Not sure, but the heated carbs may also reduce piston scuff from snow dust.
Last year with DPM, running the carb heaters on had little effect on fuel economy.
I wish you could turn them on and off without getting off the seat. There have been a couple times that I couldn't remember if I had them on or off and it bugged me until I pulled over to check (ya, know never want to be giving up performance cause I was running with them heater on, or don't want to ice up cause I forgot to turn them on, lot of good this option will do me if I don't use it properly.)
It seems that heated carbs on a sled is a more of a pain. The guy I bought my sled from said that in the "right conditions" meaning temperature, humidity, etc. they work to keep the jets from frosting up. He said wait untill you notice the sled acting funny then turn them on. Brilliant. I'd like to see a diagram of where the coolant flows through the carb to see what part gets the hottest thus affecting performance. Who would want warm gas and air going into the intake? A buddy of mine who races Pro 5.0 actually Ices his fuel and intake to cool the fuel charge for more performance.
What may make sense to me is what snowfever said in that turning them on just before shutting the sled down to warm the carbs for easier starting after a few pints may be just the ticket.
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